Low ROL (Risidual Oxygen Level) Reflow Ovens

I am looking for an inertable reflow oven which will produce ROLs of less than 10 ppm. My current reflow oven will reduce oxygen levels to 10 ppm but only when using excessive nitrogen gas (4000 scfh). In reality less gas flow may reduce oxygen levels to 10 ppm but at the cost of excessivly long oxygen purge times. I do need to nail down just how much nitrogen I really do need and how much purge time is needed. Never the less, my product is small in size, 3" square, and I am wondering if anyone makes a small footprint reflow oven which will produce 10 ppm ROLs using minimal nitrogen. I am using exotic solder alloys which do require very low ROLs. The Sikama reflow ovens use minimal amounts of nitrogen (200 scfh)and appear to be a good choice for me. I really have not found any other reflow ovens which use such a small amount of nitrogen and achieve ROLs of 10 ppm. If anyone knows of other oven manufactures which would meet my needs please comment.